On Sat, 17 Mar 2018 22:02:39 -0700, Julie Bove wrote:

> Both jars [...] deteriorated [...] black, crusty chunks
> Has anyone else ever had jars that did this?

Yes. Most likely the crud did not actually make the salsa dangerous, but
tossing it was the correct response when one considers all the bother &
suffering of just a small chance of food poisoning.

I have found this to be more common with the 'Mason' lids (two pieces; flat
disk rubberized on downward food side + cylindrical threaded portion with
interior shoulder to hold down the disc component). I suspect that
one-piece lids can be tightened more reliably by automated equipment.